6 Answers
6

A quick google search revealed a lot of possibilities, but the Chicago Transit Authority looked like it had possibilities. They even have a Bus Tracker API that might give you access to a direct feed (although I haven't even read the details, let alone tried to use the API).

Thanks. Although I won't be using Chicago, you got me looking and there is actually a similar thing for San Francisco: sfmta.com/cms/asite/nextmunidata.htm - in fact a number of municipalities seem to be using the same technology. Something called nextbus (nextbus.com/homepage). Quite interesting and ideal for what I am hoping to do. Thanks!
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Mark IrelandAug 4 '11 at 22:44

Why not just build your own? One of the coolest personal geo projects was to grab a cheapo cam, project the georeferenced frames to a 3D scene from a building, combine it with OpenCV for auto feature detection and feed that data to postgis.

Current data typically are recorded at 15- to 60-minute intervals,
stored onsite, and then transmitted to USGS offices every 1 to 4
hours, depending on the data relay technique used. Recording and
transmission times may be more frequent during critical events. Data
from current sites are relayed to USGS offices via satellite,
telephone, and/or radio telemetry and are available for viewing within
minutes of arrival.

NOAA Data

Weather data applies, too. I use a WMS call like the following in conjunction with a Google Map to quickly get local weather radar images without ads. Here's an example of the URL. I don't know how often the feed refreshes, officially, but rapid refreshing during a big weather event reveals it to be very continuous and real time. There is no telling what you'll see if you click this (if we have clear skies in Springfield you'll just get a transparent PNG):

NWS Data (a division of NOAA, but tasked with warning and advisory responsibilities)

The National Weather Service also provides some free services. I backed into the URL a little and got this page with a raw list of WMS layers you can grab. I followed the link to one of them, opened Fiddler, then selected View In.. ArcGIS.com Map, and I was able to trap a WMS URL similar to the one above and monkey with it until I got something I wanted. This example takes a Lon/Lat Bounding Box (EPSG:4326) and returns a PNG map image projected to North Aamerica Lambert Conformal Conic (EPSG:102009). This approach is repeatable for any layer you want, such as the warning/advisory polygon areas, but the radar is more likely to always show something so I used their radar: